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公路隧道围岩稳定性评价的改进人工神经网络方法 总被引:1,自引:0,他引:1
本文运用改进的人工神经网络方法 ,研究了公路隧道围岩稳定性的评价定级问题 .首先讨论了模型建立和算法选择与分析 ,并对实际的工程问题进行了计算和模拟 .所得的评价定级结果接近于实际 ,计算方法可靠 ,计算时间适中 ,方法稳定性良好 .本文的研究结果表明 ,利用人工神经网络方法评价隧道围岩的稳定性具有广阔应用前景 . 相似文献
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基于风险网络的大型工程项目风险度量方法研究 总被引:2,自引:0,他引:2
风险度量是风险管理的基础,提出适合大型工程项目风险的风险度量方法.针对大型工程项目风险因素、风险信息、风险损失之间的复杂联系,构建大型工程项目风险网络,分别采用贝叶斯网络推理和网络层次分析法获得风险发生概率和风险量的估计,从而提出基于风险网络的大型工程项目风险度量方法.方法将风险损失量和风险损失发生概率进行了明确合理的结合,既可用于度量客观风险,也可用于度量主观风险.最后以槽菁头隧道施工风险管理为例说明该方法的具体应用步骤和效果. 相似文献
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公路隧道施工存在的风险因素较多、较为复杂,运用科学的方法对公路隧道施工风险进行评估,具有一定的现实意义.首先,从地质条件、开挖断面等四个方面对风险进行划分,建立公路隧道施工风险评估指标体系.其次,运用层次分析法确定各评估指标权重,基于该权重建立层次分析-可拓模型,综合考虑公路隧道施工风险发生的概率及带来的损失,将风险定级.最后,结合湖南地区某公路隧道工程进行实例分析,得出地质条件风险、开挖断面风险、隧洞施工风险、洞口工程风险分别为高、较高、中等、较高,总体风险为较高的结论.在项目实施过程中,风险的现场调研情况与评估结果较为接近,证明了方法可行.运用层次分析-可拓模型对公路隧道施工风险评估是一种新的尝试,能够为同类问题的研究提供借鉴. 相似文献
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徐兮 《数学的实践与认识》2008,38(6):113-118
土建工程的安全质量控制的本质,就是运用数理统计原理,归纳、分析实测得到的有关数据,从而达到对现场安全作出准确诊断、对施工质量作出正确评价之目的,其中最常涉及的数学理论知识点是最小二乘原理.通过一隧道工程实例,阐明了最小二乘原理在其安全质量预测预报中的作用及使用,颇具实用性操作性地实现了数学理论与工程实际的密切结合. 相似文献
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何理礼 《数学的实践与认识》2022,(6):67-76
深埋隧洞围岩变形是一个与时间相关的复杂力学过程.为了描述这一过程,首先基于分数阶理论,提出一个新的非线性蠕变损伤本构模型.然后基于该模型,并引入Hoke-Brown屈服准则,推导出深埋条件下圆形隧洞围岩位移的黏弹塑性解析解.最后,以锦屏二级水电站辅助洞为工程实例,对解析解的有效性进行验证,并分析了流变参数对流变位移的影响.研究结果表明:1)分数阶蠕变损伤本构可以较好的描述岩石蠕变全过程,即衰减蠕变、常速蠕变及加速蠕变过程.2)随着模型中分数阶阶次及损伤因子量值的增加,围岩的蠕变变形更为明显.3)解析曲线与现场实测位移平均值曲线在量值与形态上均吻合较好,验证了解析解的有效性. 相似文献
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Wei Wang Yong-jian Yang Lian-sheng Zhang 《应用数学学报(英文版)》2007,23(1):59-66
In this paper,two auxiliary functions for global optimization are proposed.These two auxiliaryfunctions possess all characters of tunnelling functions and filled functions under certain general assumptions.Thus,they can be considered as the unification of filled function and tunnelling function.Moreover,the processof tunneling or filling for global optimization can be unified as the minimization of such auxiliary functions.Result of numerical experiments shows that such two auxiliary functions are effective. 相似文献
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应用广义Born-Oppenheimer近似理论,研究了单模腔场中二能级原子状态隧道效应的定域化控制问题,定量地分析了相干态腔场中原子手征态隧道效应的非绝热影响,给出了实现定域化的条件,还讨论了温度变化对原子态隧道效应的影响. 相似文献
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We give a necessary and sufficient condition for Heegaard splittings of knot exteriors to admit destabilizations. As an application, we show the following: let K1 and K2 be a pair of knots which is introduced by Morimoto as an example giving degeneration of tunnel number under connected sum. The Heegaard splitting of the exterior of K1#K2 derived from certain minimal unknotting tunnel systems of K1 and K2 is stabilized. 相似文献
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Let K be a knot in a sphere S3. We denote by t(K) the tunnel number of K. For two knots K1 and K2, we denote by K1?K2 the connected sum of K1 and K2. In this paper, we will prove that if one of K1 and K2 has high distance while the other has distance at least 3 then t(K1?K2)=t(K1)+t(K2)+1. 相似文献
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Oscar Perdomo 《Israel Journal of Mathematics》2006,156(1):65-71
Let (S
i, gi),i=1, 2 be two compact riemannian surfaces isometrically embedded in euclidean spaces. In this paper we show that ifM=S
1×S2,then for any functionF: M→R, the graph ofF, i.e. the manifold {(x, F(x)): x∈M}, does not have positive sectional curvature. 相似文献
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We observe a behavior of a slice (an algebraic subset) S0(K) of the -character variety of a knot group under the connected sum of knots. It turns out that the number of 0-dimensional components of S0(K) is additive under the connected sum of knots. 相似文献
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Lorenzo Mazzieri 《manuscripta mathematica》2009,129(2):137-168
In this paper we construct constant scalar curvature metrics on the generalized connected sum
M = M1 \sharpK M2{M = M_1 \, \sharp_K \, M_2} of two compact Riemannian scalar flat manifolds (M
1, g
1) and (M
2, g
2) along a common Riemannian submanifold (K, g
K
) whose codimension is ≥3. Here we present two constructions: the first one produces a family of “small” (in general nonzero)
constant scalar curvature metrics on the generalized connected sum of M
1 and M
2. It yields an extension of Joyce’s result for point-wise connected sums in the spirit of our previous issues for nonzero
constant scalar curvature metrics. When the initial manifolds are not Ricci flat, and in particular they belong to the (1+) class in the Kazdan–Warner classification, we refine the first construction in order to produce a family of scalar flat
metrics on M. As a consequence we get new solutions to the Einstein constraint equations on the generalized connected sum of two compact
time symmetric initial data sets, extending the Isenberg–Mazzeo–Pollack gluing construction. 相似文献
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Han Yoshida 《Geometriae Dedicata》2001,87(1-3):1-16
Let M be a cusped hyperbolic 3-manifold containing an incompressible thrice punctured sphere S. Suppose that M is not the Whitehead link complement. We prove that a certain arc on S is isotopic to an edge of a Euclidean decomposition of M. By using the above result, we relate alternating knot diagrams and the canonical decompositions. Let K be an alternating hyperbolic knot. On a reduced alternating knot diagram of K, if we replace one of the crossings with a large number of half twists, the polar axis of the crossing is isotopic to an edge of the canonical decomposition for the resulting knot. 相似文献
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Let M be the closed, simply connected, 4-manifold with nonnegative sectional curvature, called a nonnegatively curved 4-manifold, with an effective and isometric Z
m
-action for a positive integer m ≧ 617. Assume that Z
m
acts trivially on the homology of M. The goal of this short paper is to prove that if the fixed point set of any nontrivial element of Z
m
has at most one two-dimensional component, then M is homeomorphic to S
4, #
i
l
=1S
2 × S
2, l = 1, 2, or #
j
k
= 1 ± CP
2, k = 1, 2, 3, 4, 5. The main strategy of this paper is to give an upper bound of the Euler characteristic χ(M) under the homological assumption of a Z
m
-action as above by using the Lefschetz fixed point formula. 相似文献
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William C. Waterhouse 《Linear and Multilinear Algebra》2013,61(1-4):141-145
Take a similarity class of n × n matrices over a field K Let pi ,(λ) m(i) be the elementary divisors Li , = K [λ]/(pi ). Under conjugation by SL(n, K), the class splits into subclasses corresponding to the elements of K×/Π(NL i ×) m(i). 相似文献
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E. Ballico 《Annali dell'Universita di Ferrara》1982,38(1):33-40
Summary Here we prove the following result. Fix integersq, τ,a’, b’, a’
i, 1≤i≤τ,a’, b’, a’
i, 1≤i≤τ; then there is an integerew such that for every integert≥w, for every algebraically closed fieldK for every smooth complete surfaceX with negative Kodaira dimension, irregularityq andK
X
2
=8(1−q)−τ, the following condition holds; ifX→S is a sequence fo τ blowing-downs which gives a relatively minimal model with ruling ρ:S→C, take as basis of the Neron Severi groupNS(X) a smooth rational curve which is the total transform of a fiber ofC, the total transform of a minimal section of ρ and the total transformD
i, 1≤i≤τ, of the exceptional curver; then for everyH andL∈Pic (X) withH ample,H (resp.L) represented by the integersa’, b’, a’
i, (resp.a’, b’, a’
i), 1≤i≤τ, in the chosen basis ofNS(X) the moduli spaceM(ZX, 2,H, L, t) of rank 2H-stable vector bundles onX with determinantL andc
2=t is generically smooth and the number, dimension and ?birational structure? of the irreducible components ofM(X, 2,H, L, t)red do not depend on the choice ofK andX. Furthermore the birational structure of these irreducible components can be loosely described in terms of the birational
structure of the components of suitableM(S, 2,H’, L’, t’)red withS a relatively minimal model ofX.
Sunto SiaX una superficie algebrica liscia completa con dimensione di Kodaira negativa e definita su un campo algebricamente chiusoK; fissiamoH eL∈Pic (X),t∈Z; siaq l’irregolarità diX e τ≔8(1−q)−K X Emphasis>2 ; siaM(X, 2,H, L, t) to schema dei moduli dei fibrati vettorialiH-stabili di rango 2 suX con determinateL ec 2=t. Si dimostra che esiste una costantew che dipende solo daq, da τ e dalla classe numerica diH e diL (ma non da char (K) o dalla classe di isomorphismo diX) tale che per ognit≥w il numero, la dimensione e ?la struttura birazionale? delle componenti irriducibili diM(X, 2,H, L, t)red non dipende dalla scelta di char (K),K eX ma solo daq, τ e dalle classi diH eL inNS(X). Inoltre la ?struttura birazionale? di queste componenti irriducibili può essere grossolanamente descritta in termini delle componenti di opportuni spazi di moduliM(S, 2,H’, L’, t’) (doveS è un modello minimale diX).相似文献